Vulnerability · Published Jun 22, 2026 · Assigned by Mattermost
CVE-2026-9162Global session revocation does not invalidate active WebSocket connections
Medium 4.3
In plain English
A medium-severity security flaw in Mattermost from Mattermost. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 27% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Mattermost versions 11.7.x <= 11.7.0, 11.6.x <= 11.6.2, 11.5.x <= 11.5.5, 10.11.x <= 10.11.17 fail to invalidate cached authentication state for active WebSocket connections during global session revocation, which allows a user with an existing WebSocket connection to remain authenticated and continue receiving real-time events until the cached session expires or the client reconnects.. Mattermost Advisory ID: MMSA-2026-00664
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Go | github.com/mattermost/mattermost-server | 11.7.1 | GHSA-h998-hxxj-8q83 |
| Go | github.com/mattermost/mattermost-server | 11.6.3 | GHSA-h998-hxxj-8q83 |
| Go | github.com/mattermost/mattermost-server | 11.5.6 | GHSA-h998-hxxj-8q83 |
| Go | github.com/mattermost/mattermost-server | 10.11.18 | GHSA-h998-hxxj-8q83 |
| Go | github.com/mattermost/mattermost-server | 10.11.18+incompatible, 11.5.6+incompatible, 11.6.3+incompatible, 11.7.1+incompatible | GO-2026-6482 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Mattermost | Mattermost | 11.7.0 – through 11.7.011.6.0 – through 11.6.211.5.0 – through 11.5.510.11.0 – through 10.11.17 |
Weakness: CWE-613 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
References
- MMSA-2026-00664 vendor-advisory